Campaigners have said they believe the planned deportation to Jamaica of more than 50 people held in detention centres near Heathrow cannot go ahead, following an intervention by the Court of Appeal.
Government ministers have insisted the flight, which is understood to be leaving the UK at 6.30am on Tuesday, would go ahead despite concerns people who came to the country as young children will be on board.
The Home Office was ordered on Monday evening not to remove anyone scheduled to be deported on the flight from two detention centres near Heathrow Airport, after lawyers launched urgent proceedings amid concerns mobile phone outages had prevented access to legal advice.
Lady Justice Simler said those detainees should not be removed unless the Home Office is satisfied they "had access to a functioning, non-O2 Sim card on or before February 3".
"We are delighted with this landmark decision which is a victory for access to justice, fairness and the rule of law. On the basis of this order we do not believe that anyone currently detained at the Heathrow detention centres can be removed on tomorrow's flight." – @BellaSankeypic.twitter.com/hZQKPQUE1u
— Detention Action (@DetentionAction) February 10, 2020
The judge granted the order without a court hearing following an urgent application on paper by charity Detention Action.
The charity argued that some of the detainees at Colnbrooke and Harmondsworth detention centres still do not have a functioning mobile phone, following issues with an O2 phone mast in the area.
Bella Sankey, director of Detention Action, said: "We are delighted with this landmark decision which is a victory for access to justice, fairness and the rule of law.
"On the basis of this order from our Court of Appeal we do not believe that anyone currently detained at the Heathrow detention centres can be removed on tomorrow's flight.
"We understand that this will apply to at least 56 people."
Toufique Hossain, director of public law at Duncan Lewis who is representing at least 15 of those scheduled to be deported, said: "For weeks now detainees' complaints have fallen on deaf ears.
"Their removal looms large, hours away and yet again it takes judicial intervention to make the Home Office take basic, humane and fair steps to allow people to enjoy their constitutional right to access justice."
Some of those due to be on the flight had bids to block their deportations refused by the High Court on paper, without a hearing taking place, by the time the court closed for business on Monday.
But a spokeswoman for the judiciary confirmed other cases were still being considered, while lawyers representing those whose cases were rejected said they would press for an urgent reconsideration at an out-of-hours telephone hearing on Monday evening.
Meanwhile, protesters congregated outside Downing Street as the Government faced sustained questioning and some heavy criticism in the House of Commons over the scheduled flight.
Labour MPs shouted "shame" as Home Secretary Priti Patel left the chamber to allow junior minister Kevin Foster to respond to an urgent question on the matter for the Government.
He insisted no British nationals were on the flight and said deportation rules were applied on "the criminality, not the nationality of the offender", adding: "The foreign nationals on that flight have been sentenced to a total of 300 years in prison.
"The offences are, as we said, relate to everything from sex offending, serious drug trafficking offences, violent offences, firearms offences."
Mr Foster was repeatedly asked by MPs for more specific information on the nature of offences committed by those on the flight but refused to provide more detail.
The Home Office said murderers and rapists were among those on board but would not confirm how many, saying it could not provide such information because the flight was a live operation.
More than 150 MPs have signed a letter calling on the Prime Minister to step in and stop the flight.
The planned flight follows news of a leaked report commissioned by ministers in the wake of the Windrush scandal which warned the Government that the policy should be reconsidered in all but the "most severe cases".
Mr Hossain told the PA news agency many of the clients had come to the UK as young children aged between four and 13.
A number of the people due on the flight are thought to have been convicted of one-time drug offences when they were young and have lived in the UK "for most of their lives".
The legal proceedings were launched in light of the recommendations in the leaked Windrush Lessons Learned review that deportations of people who have been here since childhood should be stopped and reconsidered.
A draft of a report commissioned by the Government in the wake of the Windrush scandal recommended that ministers rethink the flights, particularly for those who came to the UK as children.
Written in June 2019, the document seen by PA said: "Government should review its policy and approach to FNOs (foreign national offenders), if necessary through primary legislation.
"It should consider ending all deportations of FNOs where they arrived in the UK as children (say before age of 13). Alternatively – deportation should only be considered in the most severe cases."